1. Field of the Invention
The present invention relates to high pressure pumps, and more particularly to a valve and seal assembly incorporated in such pumps.
2. Background Art
There are various applications for high pressure pumps, one being to supply very high pressure fluid (e.g., water at a pressure as high as 10,000 PSI to 100,000 PSI) so that this water may in turn be discharged in the form of a high velocity water jet which can be used for cutting, abrading, etc. A common configuration for such a pump is to employ a reciprocating piston which operates in a high pressure cylinder to direct the fluid (generally water, possibly with an additive) to a nozzle, from which the water is then discharged as the high pressure jet. On the pressure stroke, the plunger or piston can generate pressures in excess of 25,000 PSI, while during the intake stroke the pressure in the cylinder chamber is substantially reduced.
There are a number of critical problem areas associated in the design and operation of such a high pressure fluid pump assembly. It is necessary to provide a valve assembly having the appropriate valve components and intake and outlet openings, and also to provide appropriate high pressure seals. The various components of the apparatus are subjected to widely fluctuation pressure levels, and this in turn can cause some of the components to either compress or expand, depending upon the application of the force. This can have a harmful effect not only on the operation of these components, but also their durability.
The following patents were noted in a search of the patent literature, these being as follows:
U.S. Pat. No. 3,811,801 (Buce et al) shows a reciprocating pump where there is a valve assembly axially aligned with the reciprocating plunger. There are bolts 132 which secure the components of the entire assembly to one another, and one of the alleged functions of this invention is that there is not any great fluctuation in the force exerted on the bolts 132. With reference to FIG. 4 this is accomplished in the following manner. There is a discharge passageway 32 which is exposed to constant high pressure, so that the force on the high pressure area beneath the valve member 32 is exerted upwardly (as seen in FIG. 4) against the valve body 38. This would tend to counteract the high pressure in the chamber in which the plunger 102 reciprocates. There is a seal ring 136 which fits between the valve block 38 and the housing 80 which contains the high pressure piston 102, and also a seal ring 60 that fits between the valve body 38 and the cylinder head 14. An examination of the drawing would indicate that the area beneath the valve member 122 is no larger than the effective pressure area of the piston chamber against the valve member 38, so that these forces would essentially balance each other out.
U.S. Pat. No. 4,541,779 (Birdwell) shows a multi cylinder, hydraulically driven, dual arranged mud pump. In FIG. 3 there are shown 2 pumping sections. The upper pumping section in FIG. 3 is such that it draws the mud in through the end opening 88 and discharges it through the central opening 15. The lower piston and cylinder pump section in FIG. 3 does just the opposite in that the mud is drawn in through the opening 15 and discharged through the opening 88. In the lower portion of FIG. 3, there is a central block or member 11 and an end block or member 39 which are connected to each other by the tie rods 13 which would presumably hold these blocks together to form a seal with a replaceable mud pumping liner 57 (the designation 57 appears only in the upper part of FIG. 3, but denotes the inner main cylinder in which the member 66 reciprocates.) It would appear that in the lower pump section of FIG. 3, on the pressure stroke of the piston and valve member 66, the valve 51 would open so that there would be pressure inside the valve chamber. It would further appear that this pressure within the outlet valve chamber would simply be distributed in both forward and rear direction so that there would be no net force directed back toward the cylinder to create a seal.
U.S. Pat. No. 4,573,886 (Massberg et al) shows a high pressure pump where the plunger that reciprocates to create the high pressure is mounted in a sleeve. Further, there is an intake valve and outlet valve, and the flow passages of these two valves are also defined by respective sleeves. These sleeves are spaced inwardly from their housing in a manner that there is an annular gap around each of these sleeves. The high pressure fluid in the fluid chamber passes through radial openings in the sleeve of the outlet valve to pass into the annular gap around the sleeve, thus balancing the hydraulic pressure inside and outside of the sleeves. Also, fluid pressure surrounds the sleeve of the inlet valve and also the sleeve that surrounds the plunger. It is alleged that this creates a longer live for these sleeves since the stress is balanced.
U.S. Pat. No. 4,412,792 (LaBorde et al) discloses a check valve assembly for a high pressure pump having a reciprocating piston, where there is a valve insert 8 having a frusto conical configuration at the middle portion thereof, and this presses against a conically shaped matching surface of a sleeve in which the cylinder reciprocates. The inlet passages that direct the fluid into the high pressure chamber are spaced radially outwardly of the center axis of the valve insert 8 and extend through the valve insert 8. The high pressure passage extends along the center axis of the valve insert 8. In FIG. 5, there is a generally cylindrically shaped fixed member 50 through which there is a high pressure passageway 51. The member 50 is arranged so that it has a loose fit within the bore 29. Thus, high pressure fluid in the passageway 27 extends around the member 50 so that it is subjected to a constant compressive force. Thus, the high pressure forces that are created within the passage 51 on the compression stroke of the plunger are counteracted by the compressive forces around the member 50, thus improving fatigue life. It appears that the member 50 is urged by the high pressure in the passageway 27 so that it presses against the surface 56 and thus creates a seal so that the high pressure fluid in the passageway 57 would not slip by the member 50 and travel back to the pressurizing chamber on the intake stroke of the plunger.
The following patents appear to be less relevant than those discussed above, but will be treated briefly to insure that there is a disclosure of all possibly relevant prior art.
U.S. Pat. No. 4,716,924 (Pacht) shows a high pressure pump having a cylindrical plunger which reciprocates in a cylinder block. This patent is directed particularly to the configuration of the intake and discharge valves.
U.S. Pat. No. 4,432,386 and U.S. Pat. No. 4,277,229 contain the same disclosure as U.S. Pat. No. 4,716,924.
U.S. Pat. No. 4,551,077 (Pacht) shows a high pressure pump where there is a reciprocating plunger that moves along an axis, and an intake and discharge valve assembly which is mounted on the same axis as the plunger. There is an inlet valve 76 which in the seated position closes off a slanted intake passageway 66. There is a discharge passageway 86 which extends through a cylindrical portion 73 that extends axially from the valve seat 76. There is an outlet valve 88 which is positioned beyond the passageway 86 and through which the high pressure fluid is discharged.
U.S. Pat. No. 3,106,169 (Prosser et al) shows a high pressure valve and block assembly where there is a reciprocating piston 15 which discharges through the valve assembly. There are intake passages 29 and an outlet passage 19, with an outlet valve member 41. The purpose of this invention is to relieve the periodic loading on the valve members that results in the high pressure delivery piston stroke of the piston 15 and the low pressure intake stroke. The valve members are arranged so that only the members 51, 53 and 55 are exposed to the radially outward loading of the high pressure fluid going through the passageway 19.
U.S. Pat. No. 4,572,056 (Funke) discloses a plunger type pump where there is a plunger guide bushing made of a ceramic material in which a plunger made of sapphire is slideably guided. The invention resides in the discovery that the use of the hard ceramic material and the sapphire provides a match so that there is little wear.
U.S. Pat. No. 4,534,711 (Wakatsuki) discloses a high pressure pump with a reciprocating plunger. The patent is directed toward a discharge nozzle configuration where the nozzle (and therefore the water jet emitted therefrom) has a rotational motion.
U.S Pat. No. 4,456,439 (Wolff) shows a high pressure pump with a reciprocating plunger. Patentability is predicated upon the overall arrangement of the main components, particularly an L-shaped housing which holds the intake valve and the outlet valve. The inlet valve is axially aligned with the axis along which the plunger reciprocates, and the outlet valve is at right angles thereto. This provides for easy access to both valves.
U.S. Pat. No. 3,915,461 (Gautier) shows a seal for a piston which is used as a brake actuator. Patentability is predicated upon a particular configuration of the seal and groove in which the seal fits in the housing.